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Front. Neuroinform. | doi: 10.3389/fninf.2019.00044

Ictal high frequency oscillation for lateralizing patients with suspected bitemporal epilepsy using wavelet transform and Granger causality analysis

  • 1Department of Neurology, Xuanwu Hospital, Capital Medical University, China
  • 2Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University, China

Indentifying lateralization of bilateral temporal lobe epilepsy (TLE) is a challenging issue, scalp electroencephalography (EEG) and routine band electrocorticography (ECoG) fail to reveal the epileptogenic focus for further temporal lobectomy treatment. HFOs can be utilized as a biomarker for lateralizing the onset zone in suspected bitemporal epilepsy. Except subjective vision detect the HFOs, objective verification should be performed to raising the accuracy. In present research, we prospectively studied 10 patients with refractory temporal seizures and underwent electrocorticography (ECoG) with wide-band frequency amplifiers (2048Hz), all patients had a Class I outcome after temporal resection. Pre- and ictal HFOs will be analyzed by wavelet transform (WT) and Granger causality (GC) for objectively verifying lateralization of seizure onset zone (SOZ). WT analysis showed ictal HFOs in 10 patients mainly covered from 80Hz to 115 Hz (average, 92.59 ± 10.23Hz ), and there was distinct band-pass boundary between pre-ictal HFOs and ictal HFOs. GC analysis showed 5 patients (2, 4, 5, 6, 7), no matter pre-ictal or ictal state, had highest GC degree in SOZ itself. The remaining patients (1, 3, 8, 9, 10) had highest GC degree in SOZ with its adjacent regions in pre-ictal and ictal stage. GC analysis further confirmed the result of WT, and suggested HFOs is initiated and propagated in local brain region mainly, afterwards, transmitting to adjacent brain regions. These results indicated that combination of WT and GC analysis significantly contribute to accurate lateralizing patients with suspected bitemporal epilepsy.

Keywords: Bilateral temporal epilepsy, localization, lateralization, Wavelet transform, Granger casuality

Received: 15 Jan 2019; Accepted: 27 May 2019.

Edited by:

Tianyi Yan, Beijing Institute of Technology, China

Reviewed by:

Jiaojian Wang, University of Pennsylvania, United States
Bin Wang, Taiyuan University of Technology, China
Xuyuan Zheng, Tianjin Medical University, China  

Copyright: © 2019 Han, Xu, Du, Zhou, Yu, Liu and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Chunyan Liu, Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China, lcy_e_mail@163.com
Prof. Yuping Wang, Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China, doctorwangyuping@163.com